Universal precision work holder for machine tools



ug. 20, 1957 A. EISELE '2,803,064

UNIVERSAL PRECISION WORK HOLDER FOR MACHINE TOOLS Filed Oct. 22, 1952- 5Sheetss-Sheerl l INVENTOR. 26

A. EISELE Aug. zo,` 1957 UNIVERSAL PRECISION WORK HOLDER FOR MACHINETOOLS 5 Sheets-Sheet I?,

Filed 001'.. 22, -1952 m. m n m A. ElsELE UNIVERSAL PRECISION WORKHOLDER FOR MACHINE TOOLS Filed OCT.. 22, 1952 5 Sheets-Sheet 5 lINVENToR. mTew/Se/ M. @wm

United States Patent UNIVERSAL PRECISION WORK HOLDER FOR MACHINE TOOLSAndrew Eisele, Detroit, Mich.

Application October 22, 1952, Serial No. 316,220

2 Claims. (Cl. 33-174) This invention relates to machine tools and, inparticular, to work holders for machine tools.

One object of this invention is to provide a universal precision workholder for machine tools which can be adjusted with extreme accuracy bymeans of precision gauge blocks to various positions.

Another object is to provide a universal precision work holder of theforegoing character wherein the workpiece may be precisely tilted,rotated or rotated and tilted in a precise manner by the use of gaugeblocks.

Another object is to provide a universal precision work holder of theforegoing character wherein the workpiece can be precisely readjusted orindexed from one position to another to perform a plurality ofoperations on the workpiece at spaced locations thereon, thesereadjustmen'ts or indexing operations being performed with the ,use ofprecision gauge blocks.

Another object is to provide a universal precision work "holder of theforegoing character which may .be firmly ih'eld in its adjustedposition, without dan-'gerrof being shifted by the pressure of thecutter, grinding `wheel or other tool operating upon the workpiece.

Another object is to provide a universal precision Ework fz'holder ofthe foregoing character which may 4be used teither in a horizontal orvertical position, according to jthe nature of the operation to beperformed lupon the `workpiece and the type 'of machine tool to -be usedfor that purpose.

Another Objectis to provide ca universal precision work :holder of theforegoing character having supplementary ymeafnsfor additibnallysupportingth'e 'workpiece to preaventspringing or other undesired motion'thereof during :the-machining operation. t

Other objects and advantages of the invention'will belcome apparentduring the course of the following defscription of the accompanyingdrawings, wherein:

Figure l is a side elevation partly in vertical Y'section .of auniversal precision work holder for .machine tools, Aaccording toone-form of the invention;

Figure 2 is a topfplan view of the precision work holder shown in Figure1;

Figure 3 is an end elevation, partly in section, of the work holdershown in Figures 1 and 2, adjusted by means of a precision gauge blockshown'in dotted lines;

Figure 4'is an enlarged fragmentary inclined section 'taken along theinclined plane 4-4in =Figure 3, lshowing the clamping mechanism vfortheksinebar of 'the'work holder; f

Figure 5 is a side elevation similar to Figure l, but vshowing the workholder adjusted :to ianother :position by means of a precision gaugeblock shown in dotted lines, for tilting the workpiece longitudinally;

4Figure 6 is a topzplan view, partly .in horizontal section, of amodification of the precision ywork-.holder of Figures 1 to 5 inclusive,'adapted-for .use in a vertical position; l f s Figure 7is a .sideelevation, partlyin vertical section, of the modified precision workholder shown inFigure;

ice*

Figure 8 is a horizontal section taken along the line 8-8 in Figure 7,showing the mechanism for clamping the sine bar employed therewith; w

Figure 9 is a side elevation of the precision work holder of Figures lto 5 inclusive equipped with an auxiliary work support for additionallysupporting a workpiece so as to prevent springing thereof duringmachining; and

Figure 10 is a vertical section taken along the line 10-10 in Figure 1,showing the pivot construction for the precision work holder. v i y Ingeneral, the universalprecision work holder of the present invention(Figures l to 5 inclusive and 10j corisists of a stationary lower baseupon which a movable` upper base is tiltably mounted, the upper base intur'r carrying a pair of heads or brackets between which `the workpieceis mounted, either between centers or in a .chuck attached to arotatable shaft. Tilting of the upper base is precisely brought about byymeans of precision gauge blocks, and tilting or rotation of the worksupporting shaft in the head is a-lso brought about by means of lgaugeblocks in order to index the workpiece from one position to another tomachine `the workpiece precisely at a plurality of locations separatedangularly from one another. Additional support for a workpiece mountedin a chuck is provided as shown -in jFigure 9, in order to '.preventyspringing of .the workpiece duringV machining. A modification of the.previous work .holder of :the 'im/C11- .tion, shown in Figures I6, 7and 8, .enables workpieces to be mounted in Ia :vertical position .andprecisely indexed around a vertical axis. i v y Referring to thedrawings in detail, Figures 1 to y5 inclusive, -9 and l0 show auniversal precision work holder, generally designated 10, according to,one form of the invention as consisting of a Ymovable avorkpiece t`-`holding structure, generally designated 111, `including ,a

movable upper base -or 4sine plate '212 tiltably .mounted lupon astationary lower base, generally designated 13. The jstationary :lowerbase 13 consists of an elongated plate Vor block 14 provided withAspaced Vparallel longitudinal dovetail :grooves 15 vrand upstandingparallel brackets 16,the latter 'being located at one end ofthe lowerbase v13. Arranged between the dovetail grooves y15 -on'the `;plate 14is an elongated boss 17 having a preciselymachined at top contact orreference snrface18 which is vparallel to the precisely-machined bottomsurface 19 ofthe base V13. I

The brackets `16 are provided with alignedhorizontal bores '20 and alsoprovided with horizontal slots 21 extending into vthe bores 20.Mountedin thealignedbores 20 .is a pivotshaft ,22 which is adapted Atobe clamped inposition by clamping screws 23 disposed on l,opposite4sides of the bores 20 (Figure l) and threaded into screw holes 24beneath the slots 21. Consequently, yb.y,lo '1sen ing `the clampingscrews 23, the shaft 22 may be rotated,

' yand by tightening the screws 23, the shaft 122 maybe clamped'in `a.vixedjposition. .The screws 23 of courseat their upper ends rpassthrough :smooth-walled ,holes 325 aligned with -the threaded fholes `24and zlocated'inthe 'upper-Ihalf'of each bracket 16 above itsrespectiyeslots 21. .The s1ots-21 enable yielding ofther-uppershalfbf'each Ibracket 16 y.relatively:.to .the lower half forA clampingpurposes. The stationary llowerfbase 113 is :provided 'with Ybolt holes'26 bywhich :the lworkf holder S10 `may be secured to the machinetoolnupon Whic'hf'itlis used, as'by T-bolts (not shown). l

Intermediate the brackets 16 -(Figure l`0),th=e=p'ivot shaft-22 isprovided with spaced verticalscrew-holes 28 lwhich `receive screws y129threaded into-screw ghol'es30 fin, the bottom surface 31 of the-movablebase -12 directly tends upward :from lthe movable ibase Vv142 Aand isprovided vertical hole 59 for receiving with a horizontal bore 33 inwhich is mounted a xed center 34 clamped in position by a set screw 35threaded through a transverse hole 36 opening into the bore 33. The xedcenter 34 has a pointed end 37 upon which one end of a workpiece W issupported. The base 13 irnmediately above the pivot shaft 22 is providedwith a downwardly-facing groove 38 intor which the pivot shaft 22 visdrawn upwardly by means of the screws 29.

Disposed parallel to the V-groove 38 and located near the opposite endof the movable upper base 12 is .a second V-groove 39 (Figure l) inwhich a gauge block contact shaft 40 is securely held, as by the setscrews 41 passing through the holes 42 in the shaft 40 and threaded intothe screw holes 43 (Figure 3), the construction being similar to that ofthe pivot shaft 22 in the V-groove 38. This arrangement is provided forholding a precision gauge block A (Figure for positioning a workpiece X.The opposite sides 46 of the movable upper base 12 (Figures l and 3) areprovided with longitudinally-spaced staggered screw holes 47 disposed atintervals along the upper base 12 and threaded to receive horizontalbrace clamping screws 48 which are inserted through pairs of alignedholes 49 in swinging lbraces 50, the holes 49 being distributed atintervals along the length of the braces 50. The clamping screws 48 alsopass through holes 51 in collars 52 which engage the braces 50 by meansof which the braces 50 are rmly clamped against the sides 46 of theupper base 12. The holes 47 and 49 are provided in sufficient number andspacing to enable the braces 50 to be securely held in any position oftilt of the base 12 within the range of the work holder 10.

The braces 50 at their lower ends are bored transversely as at 53(Figure 3) to receive pivot pins 54, the opposite ends of which aresupported in aligned bores 55 in ears 56 rising from and forming a partof the brace brackets 57. Each of the latter is provided with anintegral guide rib 58 fitting into the dovetail groove 15 and also witha dovetail-headed bolts 60, the heads 61 of which are configured toslide to and fro in the dovetail grooves 15 and locked in position byclamping nuts 62.

The movable upper base 12 is, provided with a central ylongitudinaldovetail groove 65 parallel to the dovetail groove 15, all of which areperpendicular to the pivot shaft bores 20 and pivot shaft 22. Slidablymounted in the central dovetail groove 65 is the dovetail head 66 of aclamping bolt 67 whichpasses through a vertical hole 68 in a movablework holding head or head stock 69 which is held in position by a nut7.0 threaded on the upper end thereof (Figure 3). The upper base 12 andthe head stock 69 together form a frame structure, generally Ldesignated64. The upper portion of the dovetail slot 65 is provided with parallelside walls 71 which serve to receive an elongated parallel-sided rib ortongue 72 integral with the head stock 69 and extending downwardly fromthe at bottom surface 73 thereof. The head stock 69 is hollowed out asat 74 to provide access to the clamping nut 70 upon the clamping bolt67.

The upper portion of the head stock 69 is provided with a horizontalbore 75 (Figure l), the axis of which is parallel to the referencesurface 76 on top of the movlable base 12 along which the bottom surface73 of the head stock 69 slides, the reference surface 76 being also Yparallel to the bottom surface 77 of the movable base 12.

Rotatably mounted in the bore 75 is a rotatable work holding shaft 78having an intermediate enlarged portion or annular ange 79, the rearwardsurface 80 of which is engageable with the adjacent surface 81 of thehead stock 69. Projecting forwardly from the enlargement 79 is thecontinuation or rotatable center portion 82 of the work holding shaft78. The rotatable center portion 82 is analogous to the socalled livecenter of a lathe and has a pointed end 83 which engages the oppositeend of the workpiece W from the xed center 34, the latter beinganalogous to the so-called dead center of the lathe. The bore 75, shaft78 and pointed end 83 of the rotatable center portion 82 are, of course,coaxial with the fixed center 34 and its pointed end 37.

The workpiece W is drivingly connected to the rotatable or live center82 in any suitable way, the way shown 1n the drawings being by means ofa clamping dog, gen erally designated 85, which engages parallel flatportions 86 on the opposite sides of the adjacent ends of the workpieceW. The clamping dog consists of a pair of L-shaped oppositely-facingclamping arms 87 and 88, the nose portions 89 of which engage the flatportions 86 of the workpiece W. Clamping screws 90 pass throughcountersunk bores 91 in the clamping arm 87, likewise pass snugly butslidably through smooth-walled bores 92 in the rotatable or live center82 and are threaded into the threaded bores 93 in the clamping arm 88.In this manner, by tightening the screws 90, the arms 87 and 88 arebrought into clamping engagement with the workpiece W through theengagement of their nose portions 89 with the flat portions 86, androtary motion of the rotatable or live center 82 is accordinglytransmitted accurately to the workpiece W. In order to clamp the shaft78 in its adjusted position, the head stock 69 is provided with threadedbores 94 communicating with the bore 75 and having threaded studs orheadless set screws 95 `threaded therein into engagement with the shaft'7 8.

Mounted on the opposite end of the work supporting shaft 78 from theenlargement 79 is a collar or disc 96 (Figure 4) which is held inposition by :the set screw 97 threaded through the radial threaded bore98 and having a p ointed lower end engaging a conical depression 99 inthe shaft 78. The collar 96 has one surface 100 engaging the adjacentsurface 101 of a cutaway portion 102 of the head stock 69 whereas itsopposite surface 103 is engaged by the forward surface 104 of a sine bar105, one end of which is bored as at 106 and thereby rotatably mountedon the outer end of the shaft 78. The sine bar is retained in positionby a collar 107 and a screw 108, the latter passing through a hole 109in the collar 107 and threaded into .a threaded hole 110 in the outerend of the shaft 78.

The outer end or free end of the sine bar 105 is pro vided with acutaway portion 111 terminating in a V- notch 112 into which a Contactrod or shaft 113 is drawn by a screw 114 passing through an oblique hole115 therein and threaded into a threaded hole 116 in the contact shaft113 (Figure 3). The construction and dimensions are such that the edgeof the contact shaft 113 extends slightly outside the cutaway portion111 and is tangent to a line 117 which passes through the axis ofrotation of the work supporting shaft Vi8 and is substantially parallelto the lower edge 118 of the sine bar 105, the outer portion 119 ofwhich is offset relatively to its hub portion 120. In order to clamp thesine bar 105 in position relatively to the shaft 78, the sine `bar 105is drilled as at 121 to receive a clamping screw 122 which passesthrough a countersunk hole 123 in a collar 124 and has its threaded endthreaded into a threaded hole 125 in a clamping nut 126, the latterhaving an arcuate indentation or notch 127 engaging the collar 96.

In order t0 provide a support for a precision gauge block B, the shelf130 of the cutaway portion 102 is engaged by the lower surface 131 `of afixed gauge block supporting arm or rest 132. The arm 132 is providedwith an upper or reference surface 133 which is accurately machined to aplane surface passing through the center of rotation of the shaft 78.The inner end of the arm 132 is cut away as at 134 (Figure 3) in orderto provide clearance for the hub 120 `of the sine bar 105, and isdrilled as at 135 to receive screws 136, the lower ends of which arethreaded into threaded holes 137 in the head stock 69. In this mannerthe surface 131 of the fixed reference arm 132 is heldiirmly inengagement with the shelf Vsurface 130 of the head stock 69.

In place of the live center 82 and clamping dog 85 for holding theworkpiece W between the centers 82 and 34,

chuek 139 mayl equally well be used, as shown in the modified precisionwork holder, generally designated 140, of Figure 9. The jaw chuckv 139has a bore 141 extending through if and its'V hub 142 for receiving theinner end of the shaft 143. The latter corresponds to the shaft 78 ofFigures 1 to 5 inclusive, except that it lacks the' live center portion82 with its pointed end 8-3. The connection between the chuck 139 andthe shaft 143 is made in any suitable manner, such as by threading or,as shown, by the use of a set screw 144. The workpiece Y shown in Figure9 has a portion 145 held by the chuck jaws' 146 in the usual manner.Therchu'ck jaws 146 are moved radiallyl outward and inwardY by screwmechanism described-below in connection with the modification shownir'i- Figures 6 and 7, and theprtion 145 of the` workpiece Y is centeredin they chuck 139 in the usual way well lcown to mechanics. j

Figure 9 also shows an auxiliary work supporting" atv tachment,generally designated 150, for additionally engaging and holding theworkpiece Y in addition to the jaw chuck'139 so as to prevent springingof the workpiece during the machining operations. The auxiliarysupporting attachment 150 consists of a pair of L-shaped jaws 151 and152 which are bored as at 153 and 154 to receive d'ovetail headed bolts155 and 156 similar to the bolt 67 (Figure 3) and similarly engaging thedovetail groove 65 in the movable upper base 76. The jaw 152 is engagedand precisely adjusted by a horizontal adjusting screw 157 which isthreaded through a threaded bore 158 in a block-159. The block 159 isprovided with a vertical hole 160 for receiving a dovetail-headedclamping bolt 161 similar to the clamping bolts 155 and 156 and simiavlarly engaging the dovetail slot 65.` The holes 15S and 160 must, ofcourse, be offset relatively to one another for clearance of the screw157 relatively to the bolt 161. The' modie'd precision work holder l140shown in Figure 9 is otherwise the same as the form of the inventionshown in Figures l to inclusive and similar parts are similarlydesignated.

The modified precision work holder, generally designated 170, shown inFigures 6 to 8 inclusive, is adapted for holding a workpiece Z in avertical position. The work holder 170 consists of a base block 171 orframe structure ofapproximately L-shaped construction and having anextension 172 projecting from one end thereofrfor accommodating boltholes 173 for hold down bolts (not shown) by which the work holder 170is clamped to the bed of the machine tool upon which it is used. Thebase block 171v includes a high L-'shaped portion forming a head stock174, one side of which is hollowed out as at 175 to give access to aholddown bolt (not shown) inserted in the vertical slot 176. One side ofthe base block 171 along the extension 172 is provided with a referenceportion 177 having a vertical reference surface 178 for aA precisiongauge biock C and accurately machined to a plane surface, a continuationof which passes through the axis of a vertical bore 179 which rotatablyreceives a vertical shaft 180'. Mounted on the upper end of the shaft180 is a jaw chuck, generally designated 181, having a bore 182 thereinfor receiving thevshaft 180 and having a` radially-directed threadedhole 183 opening into, the bore 182 at right angles to the axis thereofand receiving a set screw 1784 by which the chuck 181 is anchored to theshaft 180. v v

The chuck 181 includes a cylindrical block 185 (Figure 7) having radialslots or grooves 186 in which the jaws 187 are slidably mounted andmoved to and fro by means of adjusting screws 183; The cylindrical block185 form ing the body of the chuck 181 near its bottom surface 189 isprovidedA with a circumferential groove 190 which is engaged by thearcuate nose portions 191 of holddown members 192, the latter beingdrilled as atv193 to `receive holddown or clamping screws 194 threadedinto threaded The bottom surface 196 of the base"r lfilockj 1715" iseessed as at 197 to provide an elevated su'fa 198 raised above thebottom surface 196, both of these" surfaces being accurately machined toparallelism and also to perpendicularity relatively to the axis of thebore 179 and axis of rotation of the shaft 180. Secured to the lower endof the shaft 1180, as by the collar 199 set into a countersink 200, is asine bar 201 similar in construction to the sine bar 105 previouslydescribed. The inner end of the sine bar 201 which is provided with thecountersink 200 is secured to the shaft" 180 by a screw 202 passingthroughv a countersunk bore 203 in the collar 199 into a threaded hole204in the lower end of the shaft 1180.

The sine bar 201, as in the case of the sine bar 105; is provided withan outer arm portion 205`which is cut away as at 206 to provide a'Venoteh- 207 i which a gauge block contat-'zt shaft or rod 208 for the'gauge' block C is secured as bythe screw 209 passing through the hole210 into the threaded hole 211 in the shaft 208. The construction issuch that lthe shaft 208 projects slightly beyond the adjacent edge 212of the arm portion 205 and is tangent to a line 213 passing through theaxis of rotation of the shaft 180.

In order to clamp the sine bar 201 in its adjustedposi'- tion, a disc orcollar 214 isl secured as by the screw 215 threaded through the threadedbore 216 thereof (Figure 8) into engagement with the recess 217 in theshaft 180. The disc 214 has a cylindrical periphery 218 which is engagedby a clamping dog 219 havingy a notch 220 therein to receive theperiphery of the disc `214-. The clamping dog 219' is bored as at 221 toreceive a clamping screw 222, the lower end of which is threaded into ascrew here 22s in the sine bar zur. consequently, when' the screw 222 istightened, the clamping dog 219 is drawn firmly into engagement withthe* damping disc 2714, nrmiy locking the sine bar 201- thereto. Theclamping dog 219 isprovided with an arcuate nose portion 224 and theboss 225 in which the shaft bore 179 is located is `provided with acorrespondingly arcuate edge portion 226 (Figure 8) in order to' avoidContact between these parts as the sine bar 201 is swung to and fro;

In the operation of the precision work holder 10 shown in Figures l to 5inclusive and l0, the lower or stationary base 13 is secured to the bedof the machine tool, such as a milling machine or grinder, by means ofholddown bolts inserted through the holes 26 therein. Thelworkpiece W ismounted between the centers 82 and 34 (Figure l) clamped in position bymeans of the clamping dogl 85. Assuming that the workpiece W is to becut or ground at a plurality of positions spaced at intervals aroundits. periphery, the workpiece W is set for its rst position by releasingthe clamping screws and the sine bar clamping screw 122, therebypermitting the workpiece supporting shaft 78, clamping dog 85, andworkpiece W to be rotated.A freely by hand until the starting point orfirst machine` location is properly presented to the machining tool,such :as a milling cutter or grinding wheel. It is assumed, of course,that this position has been properly laid out on the workpiece in aconventional way well-known to mechanics.

With the workpiece W properly positioned for the first cut or grind, theoperator tightens the clamping screws 95 to lock the shaft 78 in its4adjusted position (Figure 1), then swings the sine bar downward untilits contact shaft 113 engages the contact surface 133 (Figure 3) of thearm 132, whereupon he clamps the sine bar 1,05' in this zero or startingposition by tightening the clamping screw 122'. The operator then makesthe first cut o1'- grind on the workpiece W. V l

The operator then selects the proper gauge block B corresponding to thesine of the angle through which he is to rotate theworkpiece W in orderto bring it to the position desired for the second cut or grind.

After loosening the clamping screws 951th release the shaft'78',A heswings the sine'bar 105' upward', inserts the gauge bloeit.,

B between the surface 133 on the arm 132 and the contact shaft 113 onthe sine bar 105 (Figure 3). When these members are properly in contact,the workpiece W has been properly rotated or indexed to its newposition, whereupon the operator again tightens the clamping screws 95and performs the machining operation on the new position or secondposition of the workpiece W. When this has been done, he again releasesthe sine bar clamping screw 122 while holding the work supporting shaft78 tightly clamped, removes the gauge block B if he has not already doneso, swings the sine bar 105 again downward to its zero position wherethe contact shaft 113 engages the surface 133 of the arm 132 and againretightens the sine bar clamping screw 122 with the sine bar again inits zero position.

If the third cut or grind is to be made in a position spacedcircumferentially the same angle from the second position `as the secondposition was from the first position, as is frequently the case, theoperator again loosens the clamping screws 95 to release the shaft 78and again swings the sine bar 105 upward to rotate the shaft 78 andworkpiece W to its third position, again inserting the gauge block B inthe manner previously described, and as shown in Figure 3, retighteningthe clamping screws 95 to lock the shaft 78 and workpiece W in the thirdposition when the gauge block B rests upon the arm surface 133 and thesine bar contact shaft 113 rests upon the gauge block B. The operatorthen makes the third cut or grind. If, however, the third cut or grindis to be made in a position spaced a diiferent angle from the second cutor grind, then the second cut or grind is circumferentially spaced fromthe first cut or grind, the operator selects a different gauge block Bcorresponding to the sine of the desired angle of rotation of the shaft78 and workpiece W to bring it into the desired position, using it inthe same way to set the sine bar 105. The procedure is repeated as manytimes as there are ,cuts or grinds to be made.

If the workpiece X is to be machined in an axiallytilted position(Figure the operator removes the screws 48 from the braces 58 and alsoloosens the nuts 62 on the bolts 60. If the pivot shaft 22 is notsufficiently movable in its bores 20 in the brackets 16, he loosens theclamping screws 23 slightly to permit this. He then selects a gaugeblock A which corresponds to the sine of the angle through which hewishes to tilt the axis of the workpiece X relatively to the referencesurface 18, swings the movable workpiece holding structure 11 upwarduntil he can insert the gauge block A between the reference surface 18and the contact shaft 40. He permits the latter and the structure itsupports to rest upon the gauge block A (Figure 5) while he swings thebraces 50 and moves the brace brackets 57 longitudinally along theIdovetail grove 15 until he is able to reinsert the screws 48 in a newhole 47 in the movable base 12, whereupon he tightens the nuts 62 andscrews 48 to lock the braces 50 solidly in their supporting positionshown in Figure 5. Indexing operations to rotate the workpiece X aroundits axis of rotation are made in the manner described above inconnection with Figures 1 to 5 inclusive, hence require no repetition.ln this manner, for example, a frusto-conical workpiece such as theworkpiece X may lalso be machined at circumferentially-spaced locationswith cu-ts or grinds which are tilted angularly relatively to the axisthereof.

If a workpiece Y is more conveniently supported in a chuck, the modifiedposition work holder 140 of Figure 9 is used. As previously stated, thisis essentially the same as the workpiece holder of Figures l to 5 andl0, except that a chuck 139 is substituted for the clamping dog 85. Theworkpiece holder 140 in other respects is adjusted and used in exactlythe same manner as that described above for the workpiece holder 10,hence requires no repetition.

If, however, the workpiece Y requires additional support to preventspringing, the auxiliary work supporting 'attachment 1501s mounted onthe movable upper base 8 12 as described in connection with theconstruction thereof, and the jaws 151 and 152 positioned by slidingthem along the surface 76 until they properly engage the workpiece Y,whereupon their clamping bolts 155 and 156 are tightened to lock them inposition. If it is desired to move the jaw 152 by small increments, thefine adjustment screw 157 is used, after rst loosening the clamping bolt156 of the jaw 152 and tightening the clamping bolt 161 of the block159. When the desired adjustments have been made and the workpiece Y isproperly supported between the jaws 151 and 152, the clamping bolt 156is likewise tightened. This arrangement prevents springing.

of the workpiece during the machining operations and.

must of course be loosened when the workpiece Y is indexed to a newposition in the manner described above in connection with Figures 1 to 5inclusive and 10. The mode of operation is otherwise substantially thesame as described in connection with those figures.

lf a workpiece Z is to be supported and machined in a vertical position,such as, for example, to provide a plurality of angularly-spaced iiutesin the end thereof, the precision work holder of Figures 6 to 8inclusive is employed, but the foregoing principles and general mode ofoperation apply. As before, the base block 171 is bolted to the bed ofthe machine tool, such as a milling machine or grinder, by insertingT-bolts in the holes 173 and slot 176, and the workpiece Z is properlycentered in the chuck 181 by moving the jaws 187 by means of the screws188 as in conventional lathe practice. The clamping screws 194 for theholddown members 192 are loosened, likewise the clamping screw 222 forthe sine bar 285 (Figure 8). The workpiece Z is set in its lirstposition with the gauge-contacting shaft- 208 engaging the referencesurface 1'78 as a zero or starting position (Figure 6), whereupon theclamping screws 194 and 222 are tightened and the rst cut or grind ismade,

on the upper end of the workpiece Z. It will be understood, of course,that this apparatus can also be used to make cuts or grinds on the sidesof the upper end portion of the workpiece Z in a similar manner to thatdescribed in machining the upper end thereof.

Having made the first cut or grind, the operator loosens the holddownmember clamping screws 194 so as to release the holddown members 192from their clamped positions, while leaving the sine bar clamping screw222 and clamping dog 219 tightened. Having selected a gauge block Ccorresponding to the sine of the angle through which he desires to swingthe workpiece Z to the next cutting or grinding position, the operatorswings the sine bar 205, disc 214, shaft 180, chuck 181 and workpiece Zto its new position, inserts this gauge block C in the manner shown inFigure 6 with one end engaging the reference surface 178 and the otherend engaging the contact shaft 208, and then tightens the holddownmember clamping screws 194 to cause the holddown members 192 to lock thechuck 181 and workpiece Z in its new position.

The cut or grind is then taken for the second position, after which thechuck 181 and workpiece Z are indexed to their third position and tosubsequent positions by means of the sine bar 205 and gauge block C in amanner analogous to that described above in connection with Figure 3. Ifequal angular circumferential intervals are to be indexed on theworkpiece Z, the same gauge block C is used for each resettingoperation, whereas if a different angular interval is to be indexed, adifferent gauge block C corresponding to the sine of the desired angularinterval is used as described above.

What I claim is:

1. A vertical universal precision work holding and positioning fixturecomprising a base having a bottom surface thereon adapted to rest uponand be secured to the work table of a machine tool and having anupstanding portion rising from said base, a shaft rotatably mounted insaid upstanding portion upon an axis of rotation substantiallyperpendicular to said bottom surface, said base having a recess thereinin the lower portion thereof, a sine bar abutment drivingly secured tosaid shaft within said recess, a sine bar loosely and rotatably mountedon said shaft adjacent said abutment and swingable to and frohorizontally in said recess, a clamping device mounted on said sine barin releasable locking engagement with said abutment, said base having agauge block rest thereon disposed substantially perpendicular to saidbottom surface, said sine bar having a gauge block contact memberthereon aligned with said gauge block rest, and a work carrier mountedon the upper portion of said shaft above said upstanding portion forrotation with said shaft.

2. A vertical universal precision work holding and positioning xturecomprising a base having a bottom surface thereon adapted to rest uponand be secured to the work table of a machine tool and having anupstanding portion rising from said base, a shaft rotatably mounted insaid upstanding portion upon an axis of rotation substantiallyperpendicular to said bottom surface, said base having a recess thereinin the lower portion thereof, a sine bar abutment drivingly secured tosaid shaft within said recess, a sine bar loosely and rotatably mountedon said shaft adjacent said abutment and swingable to and frohorizontally in said recess, a clamping device mounted on said sine barin releasable locking engagement with said abutment, said base having agauge block rest thereon disposed substantially perpendicular to saidbottom surface, said sine bar having a gauge block contact memberthereon aligned with said gauge block rest, and a Work carrier mountedon the upper portion of said shaft above said upstanding portion forrotation with said shaft, said recess extending inwardly from one sideof said base above the level of said bottom surface and said sine barbeing disposed in said recess above the level of said bottom surface.

References Cited in the file of this patent UNITED STATES PATENTS1,295,982 Hanton Mar. 4, 1919 1,366,396 Loetler Jan. 25, 1921 2,365,436Saucier Dec. 19, 1944 2,386,880 Osplack Oct. 16, 1945 2,398,121Silvermaster Apr. 9, 1946 2,451,588 Techu Oct. 19, 1948 2,501,148 WeisMar. 21, 1950 2,504,961 Bratten Apr. 25, 1950 2,589,489 Fuhr Mar. 18,1952 2,645,067 Hinderer July 14, 1953 2,664,641 Parnet Jan. 5, 19542,706,858 King Apr. 26, 1955 FOREIGN PATENTS 569,002 Great Britain May1, 1945 606,073 Great Britain Aug. 5, 1948

